The present invention relates to methods of post-honing reciprocating-engine cylinder preparation. More specifically, the present invention relates to the use of cylinder lubricants incorporating cleanliness indicators in connection with post-honing engine assembly methods.
In the manufacture or remanufacture of reciprocating engines, it is typically necessary to bore and/or hone the engine cylinders. The processes of boring and/or honing a cylinder leave a fine contaminant residue. This residue and other contaminants (e.g., soil, dust, and corrosion particles) must be removed prior to engine assembly. A failure to remove these contaminants will result in excessive initial engine wear, shortening the overall performance life of the engine and, in some cases, posing a risk of catastrophic failure.
These boring and/or honing processes are often performed in a modest service or customization facility. Such facilities typically lack the elaborate (and expensive) cleaning instrumentality of a production-engine manufacturing facility. Adequate pre-assembly cleaning is therefore typically more of a problem for the modest service or customization facility than the production facility.
The very processes of boring and/or honing a cylinder produce process debris. This debris is typically made up of a mixture of particulate matters removed from the inner surface of the cylinder mixed and from the boring and/or honing tool, i.e., of bits of cylinder and bits of abrasive. A portion of this debris embeds itself into the inner surface of the cylinder. This embedded debris is not easily removed from the cylinder. A cylinder may be made visually clean (i.e., the cylinder contains no contaminants visible to the naked eye) and wiping clean (i.e., a white cloth used to wipe the cylinder shows no visible contaminants) without being substantially free of contaminants.
To prevent excessive wear and associated problems during engine run-in, therefore, the cylinders should be adequately cleaned prior to running the engine. A cylinder is adequately cleaned when the cleaning process has removed substantially all the contaminants upon or in the inner surface of the cylinder.
Additionally, since a reciprocating engine must already be running before its oil distribution system can lubricate the cylinders, there is a short period of xe2x80x9cdryxe2x80x9d operation during run-in, i.e., when an engine is placed into operation for the first time after boring and/or honing of the cylinders. Therefore, to prevent excessive wear and associated problems during engine run-in, the cylinders should be lubricated prior to running the engine.
A wet initial lubrication, e.g., a coating of oil, may have a tendency to attract dirt, dust, and other contaminants during engine assembly. For this reason alone, a wet lubrication is often undesirable.
Typical lubricating oil (e.g., crankcase oil) is a surface lubricant. That is, it has a relatively large molecule and lubricates by clinging to the surfaces of the parts, therefore providing a barrier to part-to-part contact. In a cylinder, where piston rings wipe the surface at each stroke, such a surface lubricant must constantly be replaced. This is a task of the engine""s lubrication system.
When such a typical lubricating oil is used to provide a wet initial lubrication, the first stroke of the piston (i.e., of the piston rings) wipes such a lubricant out of the cylinder. This leaves the cylinder dry until the oil distribution system can distribute oil to the cylinder. While short, this period of dry run-in may produce excessive wear and associated problems.
Since the inner surface of a cylinder will normally be inadequately lubricated during engine run-in, the cylinder will rapidly heat. This heating will expand the pores in the cylinder walls and release embedded contaminants therefrom if the cylinder was not adequately cleaned prior to assembly and run-in. These contaminants, made up mainly of honing debris (i.e., bits of cylinder material and bits of honing-tool abrasive) will contribute markedly to run-in wear and associated problems of the engine, possibly even catastrophic failure thereof.
To prevent excessive wear and associated problems during engine run-in, therefore, the cylinders should be both adequately cleaned and lubricated prior to running the engine. A cylinder is adequately lubricated when a penetrating lubricant is uniformly applied to the entirety of the inner surface of the cylinder. This penetrating lubricant, by being penetrating, resists being easily removed by the wiping action of the piston rings.
A problem does exist in determining when a cylinder has been adequately cleaned and lubricated. As discussed above, a visual inspection of cleanliness cannot determine if a cylinder has been adequately cleaned, i.e., if substantially all contaminants have been removed from the inner surface of the cylinder. It is desirable, therefore, to have some form of chemical indicator to detect the presence or absence of contaminants in the cylinder.
Similarly, conventional penetrating lubricants are thin lubricants, i.e., has a small molecule, in order to be penetrative. Because they are thin lubricants, typical penetrating lubricants are essentially colorless when applied. This makes it difficult if not impossible to visually ascertain if such a penetrating lubricant has been uniformly applied. It is desirable, therefore, to provide a visual indicator in the penetrating lubricant to demonstrate application uniformity.
Accordingly, it is an advantage of the present invention that an improved post-honing reciprocating-engine cylinder preparation method using a powder for piston-ring installation is provided.
It is another advantage of the present invention that the cylinder preparation method provided incorporates improved cleaning of the cylinder(s) to remove substantially all contaminants from the cylinder prior to engine assembly.
It is another advantage of the present invention that the cylinder preparation method provided incorporates an indication of cylinder cleanliness prior to engine assembly.
The above and other advantages of the present invention are carried out in one form by a method for the post-honing preparation of a cylinder of a reciprocating engine prior to assembly of the engine. The cylinder is cleaned in an effort to remove contaminants therefrom. An inner surface of the cylinder is coated with an indicating lubricant configured to assume a first predetermined tint when the contaminants have been substantially removed and a second predetermined tint when the contaminants have not been substantially removed. The engine is assembled when the indicating lubricant has assumed the first predetermined tint.